Mechanism design and tension analysis of a cable-driven humanoid-arm manipulator with joint angle feedback

A series-parallel hybrid humanoid-arm manipulator is designed by utilizing cable-driven and parallel mechanism technology. The first feature is that the control accuracy is improved by using joint angle feedback method, which is implemented by installing rotary encoder on each joint of the manipulator. The second feature is that the complete decoupling of shoulder, elbow, and wrist joint is realized by using a brake line structure. The weak coupling study for the cable-driven spherical parallel mechanism of the shoulder and wrist joint is carried out on the basis of screw theory and the basis of kinematics equation is simplified. The variation of the cable tension is discussed, and the corresponding hybrid control strategy is proposed according to the characteristics of the cable driven mechanism, and the feasibility of the mechanism and the effectiveness of the control strategy are verified by the experiment.